The invention relates to an apparatus for needling at least one yarn with at least one needle board which is reciprocatable in the needling direction, with a stitch base which is disposed opposite of the needle board and is made of an endlessly revolving brush belt and a stripper which is disposed between the stitch base and the needle board and which forms at least one guide duct for the yarn extending in the revolving direction of the brush belt and comprises in the region of said guide duct pass-through openings for the needles of the needle board.
In order to bond yarns and to secure them against untwisting it is known to needle the yarns in such a way that the yarns are pulled on a stitch base within guide ducts along their length through the needling device and are penetrated by the needles which pull fiber loops transversally to the longitudinal direction of the yarn and thus fix the yarn twist on the one hand and produce a yarn bonding on the other hand. As a result of fibers which are pulled out of the fiber structure transversally to the longitudinal direction of the yarn it is also possible to produce fancy yarns which are characterized for example by special hairiness or an enlarged volume. In order to produce such yarns the stitch bases in the form of brush belts are the obvious choice as are used in the needling of velour felt. It has been seen however that under certain circumstances not only the fibers pulled out of the yarn structure are needled in the brush belt between the bristles of the brush belt but also the yarns per se, which impairs the formation of a fibrous web by fiber loops pulled out of the yarn structure and entails difficulties in the detachment of the needled yarn from the brush belt.
The invention is thus based on the object of providing an apparatus for needling fancy yarns by needling-induced extraction of fiber loops from the yarn structure without endangering the yarn guidance on the surface of the stitch base.
Based on an apparatus of the kind mentioned above, the invention achieves this object in such a way that the guide duct is provided between guide walls engaging in the brush belt, which guide walls delimit a duct cross section which tapers towards the yarn in the region of the brush engagement.
Since as a result of this measure the guide walls delimiting the guide duct engage in the brush belt and lead the bristles of the brush belt together towards the yarn due to the tapering cross section of the duct, the bristles of the brush belt form a comparatively dense support for the yarn in the region of the guide duct. Although it allows the needling in of fibers from the fiber structure of the yarn for forming a web, it substantially prevents a penetration of the yarn into the brush belt. The bristles of the brush belt which are pushed together in the support region of the yarn are supported by the guide walls and are therefore unable to yield transversally to the revolving direction of the brush belt.
Since generally several yarns are needled parallel with respect to each other, it is provided for this case that the stripper comprises several guide ducts which are situated successively adjacent to one another and between which profiles are provided with a wedge-like shape for forming the guide walls. In order to ensure that these profiles are able to engage between the bristles of the revolving brush belt in a manner which protects the brush belt, the wedge-like profiles can comprise a sloping face side which on the feed side of the brush belt is arranged in the manner of a blade and slopes downwardly in the revolving direction of the brush belt, so that the bristles moved against the profiles are pushed apart on the face side arranged in the manner of a blade and the assemblage of bristles is divided according to the guide ducts of the stripper.